Balance: (NH4)2CO3-->NH3+H2O+CO2 ...?

Answer: KOH

Explanation:I JUST TOOK IT

Francium has the largest atomic radius due to having the highest number of energy levels and the least nuclear pull.

The correct answer is B. Francium has the largest atomic radius because it has the highest number of energy levels and the least nuclear pull. The atomic radius refers to the size of an atom, which is determined by the distance between the nucleus and the outermost electron shell.

Francium has the highest number of energy levels, which means the electrons are located farther from the nucleus, resulting in a larger atomic radius. Additionally, francium has the least nuclear pull, meaning the positive charge of the nucleus has less of an attraction on the outermost electrons, allowing them to spread out more.

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The following pairs of elements would most likely exhibit similar properties:

The chemical properties and behavior of elements are determined by the their valence electrons. Elements with the same number of valence electrons will exhibit similar chemical properties.

The number of valence electrons can be determined easily from the periodic table. In the periodic table the elements are arranged in columns and rows. Columns are called the groups and the rows are the periods. From left to right, each group is numbered from 1 to 18. The group number gives information about number of valence electrons of the element:

Elements that belong to the same group have similar chemical properties.

Potassium and Lithium are both Group 1 element and have one valence electron. They are both very reactive with water. They form an alkaline solution with water.

Neon and Krypton are both Group 18 or Noble Gases. Both elements have filled valence shells with eight electrons and are very stable and quite unreactive.

Keywords: chemical properties, groups,

Answer: Renewable fuels derived from biological matter are called biofuels.

Explanation:

Bio fuels are the fuels which are derived from plants, algae or from the waste of animals. Unlike fossil fuels they are produced from renewable resources  which can be replenished again and again.

For example; ethanol from corns and sugarcane, green diesel from algae etc.

Answer: Option (a) is the correct answer.

Explanation:

Since, it is given that energy is absorbed by the water molecules resulting in a decrease in water's temperature, that is, there will also be a decrease in the energy of molecules.

As a result, molecules will come closer to each other. This means that the diagram (a)  best illustrates the energy change of this dissolving process.

Answer:

A.

Explanation:

The energy is absorbed by the water, it means that the system is losing heat, so, the difference of energy must be negative, the initial energy must be higher than the final energy.

For the reaction happens, the reactants must gain energy to overtake the activation energy, and for that, the reaction can occur.

Only letter A represents a system that the final energy is higher than the initial, and the system gains energy at the beginning.

Final answer:

Helium is used in balloons because it is lighter than air and safely floats due to its low density and nonreactive, nonflammable properties. So the correct option is b.

Explanation:

Helium is used in balloons because it is lighter than air. This is due to helium's much lower density and atomic mass compared to the average molar mass of air. Helium's atomic mass is approximately 4.00 g/mol, while air has an average molar mass of about 29 g/mol. Hence, when a balloon is filled with helium, it floats. Another critical property of helium that makes it the gas of choice for balloons is its nonreactivity. Helium is chemically non-reactive and nonflammable, which contrasts with hydrogen, another light gas that is, however, highly flammable. This property of helium makes it safe for use in various applications like balloons, airships, and blimps. Furthermore, in environments where there is a high risk of fire or explosion, such as in welding, helium serves as an inert protective atmosphere. Finally, for deep-sea divers who operate under high pressure, a mixture of oxygen and helium is essential to avoid nitrogen narcosis, commonly known as the “rapture of the deep”.

Answer:

They are normally unreactive with other elements.

Explanation:

Study island :)

The ability of an atom to GAIN

A- There was no apparent source for the uranium salts' energy (just took the edg test)

Answer:

The correct answer is "There was no apparent source for the uranium salts’ energy."

Explanation:

Becquerel while working on X-rays accidentally discovered radioactivity. While working with uranium salts he observed that it emitted penetrating radiation that exposed photographic film. His contemporaries did not know radioactivity and hence they believed that there was no apparent source for the uranium salts’ energy.

Answer:

Explanation:

In fire and arson cases evidences like volatile fuel in the sediment debris can be collected. The debris should be collected in an air-tight container like tin or paint box and bottles so as to prevent the evaporation of the fuel. The type of fuel used for setting up the fire is an important evidence.

Plastic bags should not be used because the plastic can react with the fuel components and may react with the fuel components in debris and the evidence will become futile.

Final answer:

To find the moles of carbon in the original unknown compound, we use the mass of the carbon dioxide produced from combustion, and divide by its molar mass. This gives us the moles of carbon dioxide, which are equivalent to the moles of carbon in the sample, resulting in 0.0834 mol of carbon.

Explanation:

To determine how many moles of carbon, C, were in the original 2.50g sample of an unknown compound after combustion, we need to use the mass of carbon dioxide (CO2) produced. Every mole of CO2 contains one mole of C, so the moles of C are equal to the moles of CO2.

First, calculate the moles of CO2 using its molar mass:
Moles of CO2 = mass of CO2 / molar mass of CO2
Molar mass of CO2 is approximately 44.01 g/mol
Moles of CO2 = 3.67 g / 44.01 g/mol = 0.0834 mol

Since each mole of CO2 represents one mole of carbon, the moles of carbon in the original compound is also 0.0834 mol.

Answer:

Fluorine (F) would be least likely to form a cation

Explanation:

A cation is a positively charged atom (or molecule) which has lost electron (or electrons). Electropositive elements show a greater propensity to lose electrons and form cations. These are usually metals that are present on the left of the periodic table.

Electropositivity or the tendency to lose electrons and form cations increases on going down a group and decreases across a period. In the given examples:

Potassium, K is an alkali metal and will lose electrons readily to form a cation

Nitrogen (N), Fluorine (F) and chlorine (Cl) are all non metals which prefer to accept electrons and form anions instead. Among the three, F is the most electronegative i.e. it will prefer to accept electrons and form F- rather than F+.

Answer:

Plate tectonics refers to the plate tectonic theory. According to this theory, the earth's lithosphere is divided into many parts which are commonly known as plates. These are of two types, the continental and the oceanic crust (plate). These plates move over the less dense layer of the asthenosphere from one place to another due to the creation of convection current in the layer of the mantle. This type of current forms because of the heat energy provided from the extreme internal part of the earth. This theory was simple and universally accepted and replaced the theory of continental drift discovered by Alfred Wegener.

Answer : The resulting solution will have a pH of 7.

Explanation:

Whenever acid and base reacts with each other to form water molecule is called Neutralization reaction. This water molecules is formed from the  hydronium ion ([tex]H^+[/tex]) from acid and hydroxide ion([tex]OH^-[/tex]) from base.

When the equal volumes of acid and base of equal strength are combined, the resulting pH of the solution becomes 7.

The pH 7 value means that the solution is neutral.

Answer:

[tex]\huge \boxed{\mathrm{2}}[/tex]

[tex]\rule[225]{225}{2}[/tex]

Explanation:

[tex]\sf CH_4+ O_2 \Rightarrow CO_2 + H_2O[/tex]

Balancing the Hydrogen atoms on the right side,

[tex]\sf CH_4+ O_2 \Rightarrow CO_2 +2 H_2O[/tex]

Balancing the Oxygen atoms on the left side,

[tex]\sf CH_4+ 2O_2 \Rightarrow CO_2 +2 H_2O[/tex]

[tex]\rule[225]{225}{2}[/tex]

Final answer:

Milk of magnesia is a base with a pH greater than 7, specifically around 10.5, making it effective as an antacid. It contrasts with neutral substances, like water, and acidic substances, like wine.

Explanation:

Milk of magnesia is a base. This determination is based on its pH level, which is greater than 7. Specifically, milk of magnesia, which is largely comprised of magnesium hydroxide (Mg(OH)2), has a pH of approximately 10.5. This high pH level classifies it as a basic substance, meaning it has properties that counteract acids. This characteristic is why milk of magnesia is commonly used as an antacid to neutralize stomach acid and alleviate symptoms of indigestion and heartburn.

In comparison, substances with a pH of 7, such as pure water, are considered neutral, neither acidic nor basic. Substances like wine, with a pH less than 7, are classified as acidic. Understanding the pH scale and the properties of acids and bases is essential in chemistry and various practical applications, including medicine and nutrition.

Answer:

            Box 1  = Sodium Chloride

           Box 3  =  Covalent Bond

Explanation:

Naming NaCl:

                     Ionic compounds are named as;

          i) The positive specie is named first.

          ii) The negative specie is named after.

Example: In NaCl, Sodium is the positive cation i.e. Na⁺ hence, it is named first followed by the name of negative anion which is Cl⁻ (chloride). Therefore, the name given to NaCl is Sodium Chloride.

Covalent Bond:

                This type of bond is formed between atoms by mutually sharing their valence electrons. The type of bond depends upon the electronegativity difference between the atoms. If the electronegativeity difference is greater than the bond will be polar covalent bond or if the difference is small than the bond will be non polar colvalent bond.

The two species diverged from a common ancestor approximately 40 million years ago, calculated by multiplying the total number of mutations (eight) by the mutation rate (one mutation per 5 million years).

To estimate the time two species shared a common ancestor using a molecular clock, one must know the mutation rate and the number of mutations that have accumulated in both species since they diverged from a common ancestor. In the given problem, the molecule has a neutral mutation rate of one mutation per 5 million years. If the molecules in the two species differ by a total of eight mutations, the time since the common ancestor can be estimated by multiplying the number of mutations by the rate of mutation. Therefore, 8 mutations  imes 5 million years per mutation equals 40 million years ago.

I am unsure if this is correct (especially since I'm very late), but here are the possible answer choices to this question:

O a pure substance

O a type of a mixture

O a pure compound

O an impure substance

The answer to this is a pure substance (1st option).